Remote-controlled actuator

ABSTRACT

A remote controlled actuator includes an elongated spindle guide section and a distal end member fitted to a distal end thereof for alteration in attitude. The distal end member rotatably supports a spindle for holding a tool. The spindle guide section includes a rotary shaft for transmitting rotation of a tool rotation drive source to the spindle. An attitude altering member inserted in a guide hole is selectively advanced or retracted by an attitude control drive source. An initial attitude hold control unit controls the attitude control drive source so that an initial attitude holding force necessary to maintain the distal end member in the initial attitude can be applied to the attitude altering member. An attitude alteration control unit controls the attitude control drive source so that the attitude of the distal end member can be altered by a force larger than the initial attitude holding force.

CROSS REFERENCE TO THE RELATED APPLICATION

This application is based on and claims Convention priority to Japanesepatent applications No. 2008-233001, filed Sep. 11, 2008, and No.2008-295181, filed Nov. 19, 2008, the entire disclosures of which areherein incorporated by reference as a part of this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a remote controlled actuator for use inmedical and machine processing fields and capable of changing theattitude of a machine tool.

2. Description of Related Art

Remote controlled actuators are currently available; some are used inthe medical field for osteal treatment and some are used in themechanical processing field for drilling and cutting a bone. Any ofthose remote controlled actuators controls by remote control a machinetool fitted to a distal end of an elongated pipe of a linear or curvedconfiguration. However, since the conventional remote controlledactuator is designed solely to control only the rotation of the machinetool by remote control, difficulties have been encountered in processingof a complicated shape and processing at a site difficult to view witheyes from the outside in the medical field. Also, in the drillingprocess, the capability of processing not only the linear line, but alsothe curved configuration is often required. In addition, in the cuttingprocess, the capability is required to perform the process at a sitedeep in grooves. In the following description, conventional art andproblems inherent in the remote controlled actuator will be discussedwith reference to the medical field.

In the orthopedic field, the artificial joint replacement is well known,in which a joint, of which bone has been abraded due to bonedeterioration, is replaced with an artificial joint. The jointreplacement surgery requires a living bone of a patient to be processedto enable an artificial joint to be implanted, but in order to enhancethe strength of postoperative adhesion between the living bone and theartificial joint, such processing is required to be performed preciselyand accurately in conformity to the shape of the artificial joint.

By way of example, during the hip join replacement surgery, a thigh boneis opened to secure access of an artificial joint into the femoralmarrow cavity. In order to secure a strength of contact between theartificial joint and the bone, surfaces of contact between theartificial joint and the bore must be large and so the opening forinsertion of the artificial joint is processed to represent an elongatedshape extending deep into the bone. As a medical actuator used incutting the bone in a manner described above, the actuator is known, inwhich a tool is rotatably provided in a distal end of an elongated pipeand, on the other hand, a drive source such as, for example, a motor ismounted on a proximal end of the pipe so that the tool can be driventhrough a rotary shaft disposed inside the elongated pipe. (See, forexample, Patent Document 1 listed below.) Since in this type of medicalactuator a rotatable element that is exposed bare to the outside is onlythe tool at the distal end of the elongated pipe, the tool can beinserted deep into the bone.

The surgical operation for artificial joint replacement generallyaccompanies skin incision and muscular incision. In other words, thehuman body must be invaded. In order to minimize the postoperativetrace, it is quite often desirable that the elongated pipe referred toabove is not necessarily straight, but is moderately curved. To meetwith this desire, the following technique has hitherto been suggested.For example, Patent Document 2 listed below discloses the elongated pipehaving its intermediate portion curved double to displace an axialposition of the distal end of the pipe relative to the longitudinal axisof the proximal end of the same pipe. To make the axial position of thedistal end of the pipe relative to the longitudinal axis of the proximalend of the same pipe is also known from other publications. Also, PatentDocument 3 listed below discloses the elongated pipe rotated 180°.

-   [Patent Document 1] JP Laid-open Patent Publication No. 2007-301149-   [Patent Document 2] U.S. Pat. No. 4,466,429-   [Patent Document 3] U.S. Pat. No. 4,265,231-   [Patent Document 4] JP Laid-open Patent Publication No. 2001-17446

If in a condition, in which the artificial joint is inserted into anartificial joint insertion hole formed in the living bone, a large gapexists between the living bone and the artificial joint, a large lengthof time is required to accomplish the postoperative adhesion between theliving bone and the artificial joint and, therefore, it is considereddesirable that the gap should be as small as possible. Also, it isimportant that respective surfaces of contact between the living boneand the artificial joint be smooth, and accordingly, a high precision isrequired in processing the artificial joint insertion hole. Whatever thepipe take any shape, the working range of the tool is limited by theshape of the pipe and, therefore, it is difficult to widen the workingrange of the tool to process the artificial joint insertion hole so thatthe living bone and the artificial joint may can have smooth contactsurfaces and, yet, the gap between the living bone and the artificialjoint may be small while skin incision and muscular scission areminimized at the same time.

In general, it is quite often that the patient's bone, where anartificial joint is to be implanted, exhibits a strength lowered as aresult of aging and, in a certain case, the bone itself is deformed.Accordingly, the processing of the artificial joint insertion hole ismore difficult to achieve than generally considered.

In view of the foregoing, the applicant of the present invention hasattempted to provide a remote controlled actuator of a type, in whichthe attitude of the tool coupled to the distal end can be changed byremote control so that the processing of the artificial joint insertionhole can be relatively easily and accurately performed. This is becauseif the attitude of the tool can be changed, the tool can be maintainedat a proper attitude regardless of the shape of the pipe. It is notedthat in the case of the medical actuator having no elongated pipe usedtherein, a portion where the tool is mounted can change its attituderelative to a portion to be gripped by hand (See, for example, PatentDocument 4 listed above.), but nothing has yet been suggested in the artthat the attitude of the tool can be changed by remote control.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a remote controlledactuator of a type, in which the attitude of the tool coupled to thedistal end of the elongated pipe can be changed by remote control and inwhich the attitude of the tool can be properly maintained not onlyduring the initial attitude persistence, but also during the attitudechanging time.

The remote controlled actuator according to the present inventionincludes a spindle guide section of an elongated shape, a distal endmember fitted to a distal end of the spindle guide section through adistal end member coupling unit for alteration in attitude, and a driveunit housing coupled with a base end of the spindle guide section. Thedistal end member rotatably supports a spindle for holding a tool. Thespindle guide section includes a rotary shaft for transmitting rotationof a tool rotation drive source, provided within the drive unit housing,to the spindle and a guide hole defined therein so as to extend from oneend to the opposite end. An attitude altering or operating member havinga tip end held in contact with the distal end member is reciprocallymovably inserted within the guide hole. An attitude control drive sourcefor applying to the attitude altering member a force acting in adirection of advance and retraction is provided within the drive sourcehousing and, also, an attitude control section for controlling theattitude control drive source is provided. The attitude control sectionincludes an initial attitude hold control unit for controlling theattitude control drive source to apply to the attitude altering memberan initial attitude holding force necessary to enable the attitude ofthe distal end member to hold in an arbitrarily preset initial attitude,and an attitude alteration control unit for controlling the attitudecontrol drive source to apply to the attitude altering member a forcegreater than the initial attitude holding force being applied to theattitude altering member so that the attitude of the distal end memberis altered by selectively advancing or retracting the attitude alteringmember. In this remote controlled actuator, the initial attitude holdcontrol unit controls the attitude control drive source so as to applyan initial attitude holding force, required to enable the attitude to bemaintained in the arbitrarily preset initial attitude, to the attitudealtering member.

According to the above described construction, the rotation of the toolrotation drive source is transmitted to the spindle of the distal endmember through the rotary shaft so that the tool held by the spindle canbe rotated to perform cutting of the bone or the like. At this time, theattitude of the distal end member is determined by the balance of theexternal force, acting on the distal end member, and the thrust force ofthe attitude control drive source. Accordingly, in the event that noforce necessary to alter the attitude is applied by controlling theattitude control drive source so as to apply the initial attitudeholding force to the attitude altering member, the distal end member ismaintained in the initial attitude by means of the initial attitude holdcontrol unit of the attitude control section due to the rigidity of thedistal end member which rigidity then causes the distal end member toresume the arbitrarily preset initial attitude. By the effect of thethrust force of the attitude control drive source, the attitude of thedistal end member is maintained, that is, securement of the rigidity ofthe distal member is achieved. Also, in the event that the large forcenever experienced with acts on the distal end member when, for example,the attitude of the distal end member is to be altered, it is necessaryto increase the thrust force of the attitude control drive source inorder to maintain the attitude of the distal end member. In view ofthis, when the attitude of the distal end member is desired to bealtered, the attitude control drive source is controlled so that theforce larger than the initial attitude holding force can be applied bythe attitude alteration control unit of the attitude control section tothe attitude altering member. In this way, since the attitude of thedistal member at the time of the initial attitude is controlled by theinitial attitude hold control unit and the attitude of the distal endmember at the time of alteration of the attitude is controlled by theattitude alteration control unit, the attitude of the distal end memberand the attitude of the tool held by the distal end member can beproperly maintained not only at the time of the initial attitude, butalso at the time of alteration of the attitude.

The attitude control drive source is provided within the drive unithousing on the base end side of the spindle guide section and alterationof the attitude of the distal end member is carried out by remotecontrol. Since the attitude altering member is inserted in the guidehole, it can properly act on the distal end member at all times with nodisplacement in position occurring in a direction transverse to thelengthwise direction of the attitude altering member and, therefore, theattitude altering operation of the distal end member is performedaccurately.

In the present invention, the attitude of the distal end member can bedetermined in dependence on an amount of reciprocal movement of theattitude altering member relative to a reference position, which isdefined as a position of the attitude altering member assumed when thedistal end member is in the initial attitude. In such case, the remotecontrolled actuator of the present invention may be provided with anattitude setting device for setting a target attitude of the distal endmember, in which the attitude alteration control unit is operable toconvert the target attitude of the distal end member, preset by theattitude setting device, into an amount of advance or retraction of theattitude altering member, which corresponds thereto, and to change anamount of actuation of the attitude control drive source in dependenceon the amount of advance or retraction so converted.

As described above, if the amount of actuation of the attitude controldrive source is changed in accordance with the amount of advance orretraction of the attitude altering member, the control to alter theattitude of the distal end member can be simplified and is thereforefacilitated.

Where as hereinabove described the attitude alteration control unitcontrols the attitude control drive source, it is recommended to use anactuation amount detector for detecting the amount of actuation of theattitude control drive source and feeding an output thereof back to theattitude alteration control unit.

The use of the actuation amount detector makes it possible to accuratelydetect the amount of actuation of the attitude control drive source andwhen the output thereof is fed back to the attitude alteration controlunit, the control to alter the attitude can be performed accurately.

In the present invention, the remote controlled actuator may be furtherprovided with a reverse input preventing mechanism for preventing theattitude control drive source from actuating by the effect of a forcefrom the distal end member and, in such case, such reverse inputpreventing mechanism may be provided in the attitude control drivesource or between the attitude control drive source and the distal endmember. The reverse input preventing mechanism means an actuationtransmitting mechanism, which transmits an input from an input end, butis unable to transmit an input from an output end. Blocking oftransmission of a reverse input is accomplished by, for example,producing a difference in frictional resistance, which is brought aboutby the difference in direction of transmission of a force.

If the remote controlled actuator of the present invention is providedwith the reverse input preventing mechanism, although during the supplyof the electric power to the electrically driven actuator the attitudealtering member advances or retracts, the attitude altering member willnot advance or retract in a reverse direction even when the supply ofthe electric power is interrupted, and, hence, the thrust force obtainedduring the supply of the electric power can be maintained. In otherwords, at the time of advance or retraction, the electrically drivenactuator has to be driven instantaneously with a high output. Incontrast thereto, if no reverse input preventing mechanism is employed,a continuous output of the electrically driven actuator is required. Forthis reason, the use of the reverse input preventing mechanism makes itpossible to use a compact motor for the electrically driven actuator.Also, not only can heat emission of the electrically driven actuator besuppressed, but also the heat radiating area of the electrically drivenactuator can be minimized.

Where the reverse input preventing mechanism is employed in the remotecontrolled actuator of the present invention, the wording “initialattitude holding force necessary to enable the attitude of the distalend member to be held in an arbitrarily preset initial attitude”referred to above is to be understood as meaning a force transmitted tothe attitude control drive source through the reverse input preventingmechanism. Also, the wording “force larger than the initial attitudeholding force” referred to above is to be understood as meaning a forcecapable of altering the attitude of the distal end member through thereverse input preventing mechanism.

In the present invention, the attitude control drive source may be anelectrically driven actuator and may be driven by an electric power ofPWM wave.

If the electrically driven actuator is driven by the electric power ofPWM (Pulse-Width Modulated) wave, the amount of the electric powersupplied to the electrically driven actuator can be controlled easilyand as a result, the drive of the electrically driven actuator can becontrolled precisely.

In the present invention, the attitude control drive source can be alinear actuator. In such case, the remote controlled actuator may beprovided with a force increasing and transmitting mechanism forincreasing a thrust force of the linear actuator and then transmittingit to the attitude altering member, the force increasing andtransmitting mechanism being comprised of a lever mechanism.

The use of the force increasing and transmitting mechanism is effectiveto allow even the linear actuator, having a small thrust force, to applythe large force to the attitude altering member and, therefore, thelinear actuator can be reduced in weight.

Where the force increasing and transmitting mechanism in the form of thelever mechanism is employed, a strain sensor may be provided fordetecting a strain occurring in the lever of the force increasing andtransmitting mechanism and an external force estimating section forestimating an external force, acting on the distal end member, inreference to an output of the strain sensor.

The use of the strain sensor and the external force estimating sectionmakes it possible to estimate the external force acting on the distalend member, and a result of such estimation can be utilized in thecontrol to alter the attitude of the distal end member and/or a safetycontrol or the like of the remote controlled actuator.

In the present invention, the remote controlled actuator may be furtherprovided with an attitude altering operation piece provided outside thedrive source housing for altering the attitude of the distal end memberby causing an actuation command signal to be generated to the attitudecontrol drive source through the attitude alteration control unit bymeans of an input manipulation, in which case the attitude alteringoperation piece is capable of accomplishing the input manipulation byhands then holding the drive unit housing.

The remote controlled actuator of the construction described above issuch that while the drive unit housing is manually held, cutting of asite to be processed such as, for example, a bone is carried out withthe rotating tool held in contact with the site to be processed. Duringthe cutting, the attitude of the distal end member is altered to followthe shape or the like of the site to be processed. Since this attitudealtering operation is performed by the attitude altering operation piecewhich is maniplulatable by hands then used to hold the drive unithousing, the operator can feel the actual alteration of the attitude ofthe distal end member through his or her hands touching the operatingpieced, and therefore, alteration of the attitude can be accurately andquickly accomplished.

In the present invention, the distal end member coupling unit supportsthe distal end member for tilting motion in arbitrary direction, inwhich case the guide hole and the attitude altering member insertedwithin the guide hole may be provided at three or more locations about acenter of tilt of the distal end member and the attitude control drivesource is provided for each of the attitude altering members and theattitude of the distal end member may be altered or maintained by aneffect of balance of working forces applied from the attitude alteringmembers at those three or more locations to the distal end member.

According to the above described construction, the attitude of thedistal end member can be altered in two-axis directions.

Also, in the present invention, the distal end member coupling unitsupports the distal end member for tilting motion in arbitrarydirections, in which case the guide hole and the attitude alteringmember inserted within the guide hole may be provided at a plurality oflocations about a center of tilt of the distal end member and theattitude control drive source is provided for each of the attitudealtering members, a restoring elastic member for biasing the distal endmember to hold a predetermined attitude is provided, and the pluralattitude altering members may cooperate with each other to alter theattitude of the distal end member against a biasing force exerted by therestoring elastic member.

Even in this case, the attitude of the distal end member can be alteredin two-axis directions.

Where as hereinabove described, the attitude of the distal end membercan be altered about the two attitude altering axes, the attitudealtering operation piece may be operable to alter the attitude of thedistal end member in two directions when an actuation command signal isissued to each of the attitude control drive sources and may bemanipulatable in two directions corresponding to directions in which theattitude of the distal end member is altered.

If the attitude altering operation piece is manipulatable in twodirections corresponding to the directions in which the distal endmember can be altered in attitude, the distal end member can bemanipulated through the attitude altering operation piece so as toassume any arbitrary attitude.

In the present invention, a lock operating piece may be provided fordisabling an input manipulation of the attitude altering operationpiece.

The use of the lock operating piece makes it possible to avoid anaccidental alteration of the attitude of the distal end member, whichwould otherwise result from an erroneous operation of the attitudealtering operation piece.

In the present invention, an attitude detector may be provided fordetecting the attitude of the distal end member and an attitude displaysection for displaying the attitude of the distal end member detected bythe attitude detector.

The use of the attitude display section makes it possible to accuratelygrasp the attitude of the distal end member.

The attitude detector referred to above may be an encoder for detectingan actuation position of the attitude control drive source.

If the actuation position of the attitude control drive source isdetected by the encoder, the attitude of the distal end member can beaccurately detected.

In the present invention, the remote controlled actuator may be furtherprovided with an attitude control section for controlling the attitudecontrol drive source in dependence on an actuation command signalgenerated from the attitude altering operation piece.

The provision of the attitude control section makes it possible tochange the relation between the actuation command signal, issued fromthe attitude altering operation piece, and the actuation of the attitudecontrol drive source to suit to various conditions.

here may be provided an initial attitude operating piece for issuing anactuation command signal, necessary to cause the distal end member toassume the initial attitude, through the initial attitude hold controlunit.

If the initial attitude operating piece is employed and the attitudecontrol section includes the initial attitude hold control unit, theinitial attitude of the distal end member can be set arbitrarily asdesired, and also, the distal end member can be manually forciblyreturned to the initial attitude. As a result, the initial attitude canbe accurately resumed.

Also, a storage section may be provided for storing an actuationposition of the attitude control drive source when the distal end memberis in the initial attitude, in which case the initial attitude holdcontrol unit of the attitude control section is operable to control theattitude control drive source so as to assume the actuation position,stored in the storage section, that when the initial attitude operatingpiece is operated.

The use of the storage section makes it possible to facilitate thecontrol to reset the distal end member to the initial attitude, which isperformed by the initial attitude hold control unit of the attitudecontrol section.

In the present invention, the remote controlled actuator may be furtherprovided with a rotation operating section for operating the rotation ofthe spindle, the rotation operating section being capable of beingoperated by hands then holding the drive unit housing.

If the rotation operating section is manually manipulatable by handsthen holding the drive unit housing, rotation of the spindle and halt ofthe spindle then rotating can be performed readily at hand and as aresult, the cutting process can readily be accomplished.

BRIEF DESCRIPTION OF THE DRAWINGS

In any event, the present invention will become more clearly understoodfrom the following description of preferred embodiments thereof, whentaken in conjunction with the accompanying drawings. However, theembodiments and the drawings are given only for the purpose ofillustration and explanation, and are not to be taken as limiting thescope of the present invention in any way whatsoever, which scope is tobe determined by the appended claims. In the accompanying drawings, likereference numerals are used to denote like parts throughout the severalviews, and:

FIG. 1 is a diagram showing a remote controlled actuator in its entiretyaccording to a first preferred embodiment of the present invention;

FIG. 2A is a sectional view showing a distal end member and a spindleguide section, both forming respective parts of the remote controlledactuator;

FIG. 2B is a cross sectional view taken along the line II-II in FIG. 2A;

FIG. 2C is a diagram showing a coupling structure with which the distalend member and a rotary shaft is coupled together;

FIG. 2D is a diagram showing a housing for the distal end member asviewed from a base end side thereof;

FIG. 3 is a sectional view showing the distal end member and the spindleguide section held in a condition different from that shown in FIG. 2A;

FIG. 4 is a cross sectional view taken along the line IV-IV in FIG. 1;

FIG. 5 is an explanatory diagram showing a force acting on an attitudealtering member and a distal end member coupling unit when the distalend member of the remote controlled actuator is in the initial attitudesetting;

FIG. 6 is an explanatory diagram showing the force acting on theattitude altering member and the distal end member coupling unit whenthe distal end member of the remote controlled actuator is to be changedin attitude;

FIG. 7A is a sectional view showing the distal end member and thespindle guide section, both used in the remote controlled actuatoraccording to a second preferred embodiment of the present invention;

FIG. 7B is a cross sectional view taken along the line VII-VII in FIG.7A;

FIG. 8 is a diagram showing a schematic structure of the remotecontrolled actuator according to a third preferred embodiment of thepresent invention;

FIG. 9 is a sectional view showing the structure employed mainly withina drive unit housing of the remote controlled actuator;

FIG. 10 is a view showing the remote controlled actuator as viewed in adirection shown by X in FIG. 8;

FIG. 11 is a fragmentary enlarged view a portion of FIG. 10, showing anattitude altering tool employed in the remote controlled actuator;

FIG. 12 is a diagram showing a different example of the attitudealtering tool;

FIG. 13 is a block diagram showing a control system for the remotecontrolled actuator;

FIG. 14A is a diagram showing a display condition in an indicatoremployed in the remote controlled actuator;

FIG. 14B is a diagram showing a different display condition in theindicator employed in the remote controlled actuator;

FIG. 15A is an explanatory diagram used to explain an initial attitudecontrol and showing respective conditions of the distal end member andthe spindle guide section assumed before the initial attitude control iseffected;

FIG. 15B is an explanatory diagram used to explain the initial attitudecontrol and showing respective conditions of the distal end member andthe spindle guide section assumed after the initial attitude control hasbeen effected;

FIG. 16 is a flow chart showing the sequence of the initial attitudecontrol that is effected in the remote controlled actuator;

FIG. 17A is a sectional view showing the distal end member and thespindle guide section, both employed in the remote controlled actuatoraccording to a fourth preferred embodiment of the present invention;

FIG. 17B is a cross sectional view taken along the line XVII-XVII inFIG. 17A; and

FIG. 17C is a diagram showing the housing for the distal end member asviewed from the base end side thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first preferred embodiment of the present invention will now bedescribed with particular reference to FIGS. 1 to 4. Referring to FIG.1, a remote controlled actuator according to the first embodiment of thepresent invention includes a distal end member 2 for holding a rotarytool 1, an elongated spindle guide section 3 having a distal end towhich the distal end member 2 is coupled for displacement in attitude, adrive unit housing 4 a to which a proximal end of the spindle guidesection 3 is coupled, and a controller 5 for controlling a tool rotatingdrive mechanism 4 b and an attitude controlling drive mechanism 4 c,both accommodated within the drive unit housing 4 a. The drive unithousing 4 a cooperates with the built-in tool rotating drive mechanism 4b and attitude altering drive mechanism 4 c to form a drive unit 4.

As best shown in FIGS. 2A to 2D and 3, the distal end member 2 includesa generally or substantially cylindrical housing 11 and a spindle 13rotatably accommodated within such cylindrical housing 11 through a pairof bearings 12. The spindle 13 is of a tubular shape having a distalside opening and a shank portion 1 a of the tool 1 is engaged with asplined portion 13 a in an inner diameter of the spindle 13 with theshank portion 1 a held non-detachably by means of a detent pin 14. Thedistal end member 2 is coupled with a distal end of the spindle guidesection 3 through a distal end member coupling unit 15. The distal endmember coupling unit 15 supports the distal end member 2 fordisplacement in attitude and is comprised of a spherical bearing. Morespecifically, the distal end member coupling unit 15 includes a guidedmember 11 a in the form of an inner diameter reduced portion at a baseend of the housing 11, and a guide member 21 a in the form of a collarintegral with a constraint member 21 fixed to the tip of the spindleguide section 3. The guided member 11 a and the guide member 21 a haverespective guide faces f1 and f2 that are held in sliding contact witheach other, and those guide faces f1 and f2 have respective centers ofcurvature lying at a point O on the center line or longitudinal axis CL1of the spindle 13 of the distal end member 2, having their diametersbeing reduced towards the base end of the spindle 13. Accordingly, notonly can the distal end member 2 be immovably constrained relative tothe spindle guide section 3, but it can also be supported fordisplacement in attitude so that the attitude of the distal end member 2can be altered. FIGS. 2A to 2D illustrate the condition, in which thecenter line CL1 of the distal end member 2 and the center line CL2 ofthe spindle guide section 3 are concentric with each other and aretherefore represented by the same line. FIG. 3 illustrates the conditionin which those two center lines CL1 and CL2 are held at an anglerelative to each other.

The spindle guide section 3 includes therein a rotary shaft 22 fortransmitting a rotational force, exerted by a tool rotating drive source41 (FIG. 1) accommodated within the drive unit housing 4 a, to thespindle 13. In the illustrated example, the rotary shaft 22 is employedin the form of a wire and is capable of undergoing elastic deformationto a certain extent. Material for the wire includes, for example, metal,resin or glass fiber. The wire may be either a single wire or a twistedwire. As best shown in FIG. 2C, the spindle 13 and the rotary shaft 22are connected together by means of a joint 23 such as, for example, anuniversal joint for transmitting rotation from the rotary shaft 22 tothe spindle 13. The joint 23 includes a groove 13 b, defined in a closedbase end of the spindle 13, and a projection 22 a defined in a distalend of the rotary shaft 22 and engageable in the groove 13 b. The centerof joint between the groove 13 b and the projection 22 a is located atthe same position as the centers of curvature O of the guide faces f1and f2. It is, however, to be noted that the rotary shaft 22 and theprojection 22 a may be formed of members separate from each other.

The spindle guide section 3 includes an outer shell pipe 25 forming anouter shell of the spindle guide section 3 and the rotary shaft 22referred to above is positioned at the center of this outer shell pipe25. The rotary shaft 22 so positioned is rotatably supported by aplurality of rolling bearings 26 positioned spaced a distant apart fromeach other in a direction axially of the spindle guide section 3. Springelements 27A and 27B for generating preloads on the correspondingrolling bearings 26 are disposed between the neighboring rollingbearings 26. Each of those spring elements 27A and 27B is employed inthe form of, for example, a compression spring. There are the springelement 27A for inner ring for generating the preload on the inner ringof the rolling bearing 26 and the spring element 27B for outer ring forgenerating the preload on the outer ring of the rolling bearing 26, andthe both 27A and 27B are arranged alternately relative to each other.The constraint member 21 referred to previously is fixed to a pipe endportion 25 a of the outer shell pipe 25 by means of a fixing pin 28 andhas its distal end inner peripheral portion supporting the distal end ofthe rotary shaft 22 through a rolling bearing 29. It is, however, to benoted that the pipe end portion 25 a may be a member separate from theouter shell pipe 25 and may then be connected with the outer shell pipe25 by means of, for example, welding.

As best shown in FIG. 2B, three guide pipes 30 are interposed between aninner diametric surface of the outer shell pipe 25 and the rotary shaft22 so as to extend between the both ends and are positioned atrespective circumferential position spaced 120° in phase from each otherwithin the outer shell pipe 25. Also, attitude altering or operatingmembers 31 (31U, 31L and 31R), each made up of a plurality of balls 31 aand pillar shaped pins 31 b at opposite ends, both of which form a forcetransmitting member, are axially movably inserted within respectiveguide holes 30 a of guide pipes 30, which guide holes 30 a arerepresented by respective inner diametric holes of those guide pipes 30.The balls 31 a and the pillar shaped pins 31 b are arranged in a row inline with each other in a direction lengthwise of the guide hole 30 awith no gap formed between those elements. One of the pillar shaped pins31 b, which is on the side of the distal end member 2, has its tiprepresenting a spherical shape and held in contact with a bottom surfaceof a groove 11 b formed in a base end face of the housing 11. The groove11 b and the pillar shaped pin 31 b altogether form a rotationpreventing mechanism 37, which serves to prevent the distal end member 2from rotating about the center line CL1 of the distal end member 2relative to the spindle guide section 3 when a tip end portion of thepillar shaped pin 31 b engaged in the groove 11 b is brought intoengagement with a side face of the groove 11 b. The pillar shaped pin 31b on the drive unit housing 4 a also has its tip representing aspherical shape and engaged with a side face of a lever 43 b as will bedescribed in detail later.

Also, between the inner diametric surface of the outer shell pipe 25 andthe rotary shaft 2, a plurality of reinforcement shafts 34 are arrangedseparate from the guide pipes 30 and on the pitch circle C of the samediameter as the guide pipes 30. Those reinforcement shafts 34 are usedto secure the rigidity of the spindle guide section 3. The guide pipes30 and the reinforcement shafts 34 are arranged equidistantly relativeto each other around the rotary shaft 22. The guide pipes 30 and thereinforcement shafts 34 are held in contact with the inner diametricsurface of the outer shell pipe 25 and respective outer peripheralsurfaces of the rolling bearings 26. In this manner, the outer diametricsurfaces of those rolling bearings 26 are supported.

As best shown in FIGS. 1 and 4, the tool rotating drive mechanism 4 bincludes a tool rotating drive source 41. This tool rotating drivesource 41 is in the form of, for example, an electric motor, having itsoutput shaft 41 a coupled with a base end or proximal end of the rotaryshaft 22. The attitude control drive mechanism 4 c includes threeattitude control drive sources 42 (42U, 42L and 42R) cooperablerespectively with attitude altering members 31 (31U, 31L and 31R). Theattitude control drive sources 42 are in the form of electrically drivenlinear actuators driven by an electric power of PWM (Pulse-WidthModulated) waves and the rotary motion of a rotary motor (not shown)built therein is transmitted to an output rod 42 a after having beenconverted into a linear motion by means of a rotary-linear motiontranslating mechanism, which concurrently serves as a reverse inputpreventing mechanism 45. The output rod 42 a is movable in a directionleftward and rightward as viewed in FIG. 1 and the amount of movement ofthe output rod 42 a, that is, the amount of actuation of the attitudecontrol drive source 42 is detected by an actuation amount detector 46,which is in the form of an encoder.

For the rotary-linear motion translating mechanism, a feed screwmechanism of a sliding screw type such as, for example, a triangularscrew or a trapezoidal screw can be employed. Because of the use of thefeed screw mechanism of such a sliding screw type, the attitude controldrive source 42 has a reverse input preventing function to avoid apossible operation caused by a force from the attitude altering member31. For the rotary-linear motion translating mechanism, a ball screw ora rack and pinion mechanism may be employed other than the sliding screwtype. In such case, the reverse preventing mechanism 45 has to beemployed separately. For the reverse input preventing mechanism 45employed in such case, a worm gear or the like can be employed. Otherthan those, a speed reducer having a large gear ratio can also beemployed.

It is to be noted that the reverse input preventing mechanism 45 may notnecessarily be provided in the attitude control drive source 42, but maybe provided somewhere in the attitude control drive mechanism 4 c, thatis, between the attitude control drive source 42 and the attitudealtering member 31.

The linear movement of the output rod 42 a is transmitted to theattitude altering member 31 through a force increasing and transmittingmechanism 43. The force increasing and transmitting mechanism 43includes a pivot lever 43 b pivotable about a support pin 43 a and is sodesigned and so configured as to allow a force of the output rod 42 a towork on a working point P1 of the lever 43 b, which is spaced a longdistance from the support pin 43 a, and as to apply a force to theattitude altering member 31 at a force point P2, which is spaced a shortdistance from the support pin 43 a, wherefore an output of the attitudealtering drive source 42 can be increased and then transmitted to theattitude altering member 31. A strain inducing portion 43 ba having asmall wall thickness is provided at an intermediate portion of the lever43 b and a strain sensor 47 for detecting the strain generated in thestrain inducing portion 43 ba is fitted to each of the opposite sides ofthe strain inducing portion 43 ba. The rotary shaft 22 is passed throughan opening 44 defined in the lever 43 b.

The controller 5 includes a computer 5A, a manually operable rotationalspeed setting device 50 for manually providing an input to the computer5A and an attitude setting device 51. The rotational speed settingdevice 50 is used to set a rotational speed of the spindle 13. Theattitude setting device 51 is used to set an target attitude that is tobe assumed by the distal end member 2 relative to the spindle guidesection 3. The computer 5A of the controller 5 in turn includes a toolrotation control section 52 for controlling the tool rotating drivesource 41, an attitude control section 53 for controlling each of theattitude control drive sources 42 and an external force estimatingsection 54 for estimating an external force acting on the distal endmember 2.

The tool rotation control section 52 is operable to provide a motordriver 55 with an output signal in correspondence with an input signalfrom the rotational speed setting device 50 to thereby drive the toolrotating drive source 41.

The attitude control section 53 includes an initial attitude holdcontrol unit 53 a and an attitude alteration control unit 53 b. Theinitial attitude hold control unit 53 a and the attitude alterationcontrol unit 53 b are operable to supply respective output signals to amotor driver 56 in correspondence with an input signal or the like fromthe attitude setting device 51 to thereby drive the attitude controldrive sources 42.

The initial attitude hold control unit 53 a is operable to control eachof the attitude control drive sources 42 so that an initial attitudeholding force F0 (FIG. 5) for enabling the distal end member 2 to holdan arbitrarily preset initial attitude can be applied to the attitudealtering member 31. The attitude of the distal end member 2 isdetermined by the balance between the external force, acting on thedistal end member 2, and a thrust force of each of the attitude controldrive sources 42. In view of this, when the attitude control drivesources 42 are so controlled as to apply the initial attitude holdingforce F0 to the attitude altering member 31, the distal end member 2 canbe held in the initial attitude. Holding of the attitude of the distalend member 2, that is, securement of the rigidity of the distal endmember 2 is accomplished by the thrust force of the attitude controldrive sources 42. Thus, where no force necessary to alter the attitudeis applied, the rigidity is applied by the initial attitude hold controlunit 53 a so that the distal end member can 2 resume and maintain thearbitrarily preset initial attitude.

The arbitrarily preset initial attitude referred to above may be eitheran attitude, in which the center line CL1 of the distal end member 2 andthe center line CL2 of the spindle guide section 3 are concentricallyaligned with each other as shown in FIG. 5, or an attitude in which thecenter line CL1 of the distal end member 2 and the center line CL2 ofthe spindle guide section 3 are at an angle relative to each other andare therefore bent relative to each other as shown in FIG. 6.

The attitude alteration control unit 53 b referred to above is operableto control each of the attitude control drive sources 42 so that a forceF5 larger than the initial attitude holding force F0 referred topreviously can be applied to the attitude altering member 31 toselectively advance or retract the attitude altering member 31 tothereby change the attitude of the distal end member 2. When theattitude of the distal end member 2 is to be altered, a force largerthan that during sustainment of the initial attitude, that is, duringthe standstill acts on the distal end member 2 as will be described indetail later. Accordingly, when the attitude of the distal end member 2is to be altered, the attitude control drive source 42 is so controlledas to enable the force F5, larger than the previously described initialattitude holding force F0 necessary to maintain the attitude of thedistal end member 2, to be applied to the attitude altering member 31.The attitude of the distal end member 2 is determined by the amount ofadvance or retraction of the attitude altering member 31 relative to areference position, which is the position of the attitude alteringmember 31 assumed when the distal end member 2 is in the initialattitude.

More specifically, the attitude alteration control unit 53 b is operableto convert the target attitude of the distal end member 2 relative tothe previously described initial attitude preset by the attitude settingdevice 51, into the amount of advance or retraction of the attitudealtering member 31, which corresponds to the target attitude, and thento change the amount of actuation of the attitude control drive source42 in dependence on the converted amount of advance or retraction. Sincethe amount of actuation of the attitude control drive source 42 ischanged in dependence on the amount of advance or retraction of theattitude altering member 31, the attitude altering control of the distalend member 2 can be simplified and facilitated.

Also, when the above described control takes place, control is effectedby feeding the amount of actuation of the attitude control drive source42, then detected by the actuation amount detector 46, back to theattitude alteration control unit 53 b. The provision of the actuationamount detector 46 is effective to enable the amount of actuation of theattitude control drive source 42 to be detected accurately and, when anoutput therefrom is fed back to the attitude alteration control unit 53b, the attitude altering control can be accomplished accurately.

The external force estimating section 54 referred to previously includesa relation setting module (not shown), in which a relation between theexternal force acting on the distal end member 2 and the respectiveoutput signals of the strain sensors 47 are set in terms of anarithmetic expression and/or a table or the like, and utilizes therelation setting module to estimate the external force, then acting onthe distal end member 2, from respective signals inputted from thestrain sensors 47.

The operation of the remote controlled actuator of the structurehereinabove described will now be described.

When the tool rotation drive source 41 is driven, a rotational forcethereof is transmitted to the spindle 13 through the rotary shaft 22,accompanied by rotation of both of the spindle 13 and the tool 1. By thetool 1 so rotated, cutting of the bone takes place.

When the distal end member 2 is in the initial attitude, each of theattitude control drive sources 42 is controlled by means of the initialattitude hold control unit 53 a so as to maintain the distal end member2 in the initial attitude. At this time, the predetermined initialattitude holding force F0, composed of the thrust force of the attitudecontrol drive source 42, and a reactive force thereto act on each of theattitude altering members 31 as shown in FIG. 5. FIG. 5 is a diagramcorresponding to a simplified form of the cross section taken along theline V-CL2-V in FIG. 2B, and only the upper and left attitude alteringmembers 31U and 31L are shown. As a matter of course, the initialattitude holding force F0 referred to above equally acts on the rightattitude altering member 31R which is not shown in FIG. 5. Thus, whenthe initial attitude holding force F0 is applied to each of the attitudealtering members 31, the balance of the forces acting on the distal endmember 2 can be preserved and the attitude of the distal end member 2can therefore be maintained.

During the use, each of those attitude control drive sources 42 isdriven and the attitude of the distal end member 2 is altered by remotecontrol. By way of example, when one of the attitude altering members31, i.e., the attitude altering member 31U, which is positioned in anupper area in FIGS. 2A to 2D, is advanced towards a tip end side whilethe remaining two attitude altering members 31L and 31R are retracted,the housing 11 of the distal end member 2 is pressed by the upperattitude altering member 31U with the attitude of the distal end member2 being consequently altered along the guide faces f1 and f2. Thus, thetip end side can be oriented downwards as shown in FIG. 2A, therebyassuming the condition as shown in FIG. 3. It is to be noted that theattitude altering members 31L and 31R are, when the attitude controldrive sources 42L and 42R are driven in respective directions reverse tothe direction in which the attitude control drive source 42U is driven,retracted by the housing 11 of the distal end member 2 then pressingsuch attitude altering members 31L and 31R.

Also, when, while the upper attitude altering member 31U is heldstandstill, the left attitude altering member 31L is advanced towardsthe tip end side and, on the other hand, the right attitude alteringmember 31R is retracted, the housing 11 of the distal end member 2 ispressed by the left attitude altering member 31L with the distal endmember 2 consequently oriented rightwards, that is, towards a sidereverse to the plane of the sheet of FIG. 2A along the guide faces f1and f2, thus changing the attitude.

Because of the provision of the attitude altering members 31 at threelocations in the circumferential direction, the distal end member 2 canbe altered in attitude in two-axis directions (X-axis and Y-axisdirection) i.e., upwards or downwards and leftwards or rightwards.

The pressures from the three attitude altering members 31 and thereactive force from the constraint member 21 act on the distal endmember coupling unit 15, and depending on the balance of those workingforces, the attitude of the distal end member 2 is determined. Since thehousing 11 of the distal end member 2 is pressed by those three attitudealtering members 31, the attitude stability of the distal end member 2is high.

Taking the attitude alteration of the distal end member 2 around theX-axis for instance, the thrust force of the attitude control drivesource 42U that is required for the attitude alteration will now bediscussed in detail. FIG. 6 illustrates forces F1 to F5 which act oneach of the attitude altering members 31 and the distal end membercoupling unit 15 at the time of alteration of the attitude of the distalend member 2. F1 represents an attitude holding force and a reactiveforce thereof, which act on the upper attitude altering member 31U atthe time of alteration of the attitude. The attitude holding forcereferred to above is comprised of a thrust force of the attitude controldrive source 42. F2 represents a frictional force generated when theupper attitude altering member 31U is advanced towards the tip end side.F3 represents a frictional force generated between the guide faces f1and f2 of the distal end member coupling unit 15. F4 represents africtional force generated when the left and right attitude alteringmembers 31L and 31R are retracted. More specifically, respectivefrictional forces are generated in the left and right attitude alteringmembers 31L and 31R and the sum of those frictional forces in theattitude altering members 31L and 31R is represented by the force F4. F5represents the thrust force of the attitude control drive source 42Urequired to advance the upper attitude altering member 31U towards thetip end side. The following relations establish among those forces F1 toF5:

F5>F2+F3+F4+F1  (1)

Since F1≈F0 (initial attitude holding force), the equation (1) above canbe rewritten as follows:

F5>F2+F3+F4+F0  (2)

In other words, the thrust force F5 of the attitude control drive source42U is greater than the initial attitude holding force F0 to which thevarious frictional forces F2, F3 and F4 are added. For example, thethrust force F5 is about twice the initial attitude holding force F0. Asdescribed above, when the attitude control drive source 42U is socontrolled that the force F5, which is greater than the initial attitudeholding force F0, can be applied to the attitude altering member 31U,the distal end member 2 can be altered in attitude.

As discussed above, when the attitude of the distal end member 2 duringthe standstill condition is controlled by the initial attitude holdcontrol unit 53 a and the attitude of the distal end member 2 during thealteration of the attitude is controlled by the attitude alterationcontrol unit 53 b, the attitude of the distal end member 2 and theattitude of the tool 1 held thereby can be properly maintained not onlyduring the standstill but also during the attitude alteration.

As hereinabove described, the attitude control drive source 42 is drivenby an electric power of the PWM wave and has a reverse input preventingfunction. Accordingly, the attitude altering member 31U operates in thefollowing manner. In other words, while the attitude altering member 31Uadvances when the PWM wave is ON (active with an electric powersupplied), due to the reverse input preventing function, the attitudealtering member 31U does not retract even when the PWM wave is OFF(inactive with the supply of the electric power interrupted) and theadvanced position is maintained when the PWM wave is ON. In other words,the attitude altering member 31U undergoes continuous repetition ofminute advances. In contrast thereto, if there is no reverse inputpreventing function in the attitude control drive source 42, theattitude altering member 31U retracts when the PWM wave is OFF, and,therefore, the amount of actuation of the attitude altering member 31Urepresents an average between the amount of advance, effected when thePWM wave is ON, and the amount of retraction effected when the PWM waveis OFF. Accordingly, as compared with the case of the reverse inputpreventing function not provided in the attitude control drive source42, the structure according to the foregoing embodiment of the presentinvention is effective to secure a large amount of actuation as a whole.For this reason, a compact motor can be advantageously employed in theattitude control drive source 42, which is an electrically drivenactuator. Also, not only can the heat emission from the attitude controldrive source 42 be suppressed, but also a heat dissipating unit of theattitude control drive source 42 can be fabricated in a compact size.

Yet, as best shown in FIG. 1, since the force increasing andtransmitting mechanism 43 is provided, the large force can be applied tothe attitude altering member 31 even with the attitude control drivesource 42 capable of exerting a small thrust force. In view of this, theattitude control drive source 42 can be fabricated in a compact size.

When an external force acts on the distal end member 2 or the tool 1during the cutting operation, a force thereof is transmitted to thelever 43 b of the force increasing and transmitting mechanism 43 throughthe attitude altering member 31, resulting in strain in the straininducing portion 43 ba, which is a fragile portion. This strain is inturn detected by the strain sensor 47 and an output signal thereof istransmitted to the external force estimating section 54. The externalforce estimating section 54 estimates the external force, then acting onthe distal end member 2, from the output signal of the strain sensor 47.When the amount of feed of the remote controlled actuator as a whole andthe alteration of the attitude of the distal end member 2 are controlledin dependence on the magnitude of the external force estimated in themanner as hereinabove described, the bone can be cut securely andaccurately while the external force acting on the distal end member 2 isproperly maintained.

Also, the rotation preventing mechanism 37 prevents the distal endmember 2 from rotating about the center line CL1 of the distal endmember 2 relative to the spindle guide section 3. Accordingly, even whenthe distal end member 2 then holding the tool 1 becomes unable to becontrolled by reason of a trouble occurring in the attitude controlsection 53 and/or the attitude operating drive mechanism 4 c forcontrolling the selective advance and retraction of the attitudealtering member 31, it is possible to avoid the possibility that thesite to be processed may be impaired as a result of rotation of thedistal end member 2 about the center line CL1 or the distal end member 2itself may be broken.

Since the attitude altering member 31 is inserted through the guide hole30 a, the attitude altering member 31 can act properly on the distal endmember 2 at all times without being accomplished by displacement inposition in a direction perpendicular to the lengthwise directionthereof, and therefore, the attitude altering operation of the distalend member 2 can be performed accurately. Also, since the attitudealtering member 31 includes the plurality of the balls 31 a and thepillar shaped pins 31 b and has a flexible property in its entirety, theattitude altering operation of the distal end member 2 is assuredlycarried out even though the spindle guide section 3 is curved. Inaddition, since the center of the junction between the spindle 13 andthe rotary shaft 22 lies at the same position as the respective centerof curvature O of the guide faces f1 and f2, no force tending to pressand pull will act on the rotary shaft 22 as a result of alteration ofthe attitude of the distal end member 2 and, therefore, the distal endmember 2 can be altered in attitude smoothly.

The remote controlled actuator according to the embodiment is used ingrinding the femoral marrow cavity during, for example, the artificialjoint replacement surgery and during the surgery, it is used with thedistal end member 2 in its entirety or a part thereof inserted into thebody of a patient. For this reason, if the distal end member 2 can bealtered in attitude by remote control, the bone can be processed in acondition with the tool 1 maintained in a proper attitude at all timesand, therefore, the opening for insertion of the artificial joint can befinished precisely.

There is necessity that the rotary shaft 22 and the attitude alteringmember 31 are provided in a protected fashion. In this respect, thespindle guide section 3, which is elongated in shape, is provided withthe rotary shaft 22 at the center of the outer shell pipe 25 and theguide pipes 30, accommodating therein the attitude altering member 31,and the reinforcement shafts 34, all of these are arranged in thecircumferential direction and between the outer shell pipe 25 and therotary shaft 22. Accordingly, the rotary shaft 22 and the attitudealtering member 31 are protected and the interior can be made hollow tothereby reduce the weight without sacrificing the rigidity. Also, thearrangement balance as a whole is rendered good.

Since the outer diametric surfaces of the rolling bearings 26 supportingthe rotary shaft 22 are supported by the guide pipes 30 and thereinforcement shafts 34, the outer diametric surfaces of the rollingbearings 26 can be supported with no need to use any extra member. Also,since the preload is applied to the rolling bearings 26 by means of thespring elements 27A and 27B, the rotary shaft 22 in the form of a wirecan be rotated at a high speed. For these reasons, since the processingcan be accomplished with the spindle 13 rotated at a high speed, a goodfinish of the processing can also be obtained and further, the cuttingresistance acting on the tool 1 can be reduced. Since the springelements 27A and 27B are disposed between the neighboring rollingbearings 26, the spring elements 27A and 27B can be provided with noneed to increase the diameter of the spindle guide section 3.

While the foregoing embodiment has been shown and described, in whicheach of the guide pipe 30 and the attitude altering member 31 isprovided at three locations in the circumferential direction, thepresent invention is equally applicable to the arrangement, in whicheach of the guide pipe 30 and the attitude altering member 31 isarranged at two locations within the outer shell pipe 25 in a fashionspaced 180° in phase from each other in the circumferential direction asshown in FIGS. 7A and 7B showing a second preferred embodiment of thepresent invention. In such case, the distal end member 2 can be alteredin attitude only about the X-axis.

A third preferred embodiment of the present invention will behereinafter described in detail with particular reference to FIGS. 8 to16. In the third embodiment shown in FIGS. 8 to 16, component partssimilar to or identical with those shown and described in connectionwith the first embodiment of the present invention are designated bylike reference numerals used therein and the details are not reiteratedfor the sake of brevity. The remote controlled actuator shown in FIG. 8and pertaining to the third embodiment of the present invention is madeup of an actuator body 6 and a control box 7 connected with the actuatorbody 6 through an electric cable 8.

The actuator body 6 is made up of a distal end member 2 for holding therotary tool 1, which has been described in connection with thepreviously described first embodiment of the present invention, anelongated spindle guide section 3 having the distal end member 2 fittedto a distal end of thereof for alteration in attitude, and a drive unithousing 4 a to which a base end of the spindle guide section 3 iscoupled. The drive unit housing 4 a cooperates with the built-in toolrotating drive mechanism 4 b and an attitude altering drive mechanism 4c to define a drive unit 4.

The distal end member 2 and the spindle guide section 3, both employedin the remote controlled actuator according to the third embodiment ofthe present invention, are similar to those shown in and described withreference to FIGS. 2A to 2D in connection with the previously describedfirst embodiment and the details thereof are not therefore reiteratedfor the sake of brevity. The attitude altering drive mechanism 4 creferred to above includes three attitude control drive sources 42 (42U,42L and 42R) corresponding respectively to the attitude altering members31 (31U, 31L and 31R) in a manner similar to those employed in thepreviously described first embodiment. The attitude control drivesources 42 are employed in the form of, for example, electrically drivenlinear actuators and movement of an output rod 42 a thereof movableleftwards and rightwards as viewed in FIG. 9 is transmitted to theattitude altering member 31 through the force increasing andtransmitting mechanism 43. The position of selective advance orretraction of the output rod 42 a of each of the attitude alteringmembers 31, that is, the position of activation of each of the attitudecontrol drive sources 42, is detected respectively by an attitudedetector 48 (48U, 48L and 48R) each in the form of an encoder. Thisattitude detector 48 is of a type capable of performing the samedetecting operation as the activation amount detector 46 shown in FIG.1.

As shown in FIGS. 8 and 10, left and right side faces of the drive unithousing 4 a is provided with a pair of left and right handles 50L and50R. As shown by the double dotted chain line in FIG. 10, the actuatorbody 6 can be held with the handles 50L and 50R gripped by oppositehands.

The left handle 50L has a tip end provided with a rotation ON/Offoperating piece 57, or a rotation operating section, for selectivelyrotating or halting the spindle 13. Also, the left handle 50L has anupper face provided with a lock operating piece 49 for halting thefunction of an attitude altering operation piece 58 as will be describedin detail later. Each of the rotation ON/OFF operating piece 57 and thelock operating piece 49 is in the form of a push button switch and canbe manipulated by a left hand then gripping the left handle 50L.

The right handle 50R has its tip end provided with the attitude alteringoperation piece 58 for altering the attitude of the distal end member 2.As shown in FIG. 11 on an enlarged scale, the attitude alteringoperation piece 58 is a crisscross switch having four operating piecesarranged in a cross form and those four operating pieces are representedrespectively by an upper tilt operating piece 58 a for tilting thedistal end member 2 so as to be oriented upwardly, a lower tiltoperating area 58 b for tilting it so as to be oriented downwardly, aleft tilt operating piece 58 c for tilting it so as to be orientedleftwards, and a right tilt operating piece 58 d for tilting it so as tobe oriented rightwards. Those operating pieces 58 a, 58 b, 58 c and 58 dof the attitude altering operation piece 58 can be each manipulated bythe right hand then gripping the right handle 50R.

The attitude altering operation piece 58 may be in the form of ajoystick as shown in FIG. 12. The attitude altering operation piece 58,which is in the form of a joystick, includes a lever 58 e having afreedom in two directions. When this lever 58 e is tilted upwards, thedistal end member 2 is tilted upwards; when the lever 58 e is tilteddownwards, the distal end member 2 is tilted downwards; when the lever58 e is tilted leftwards, the distal end member is tilted leftwards; andwhen the lever 58 e is tilted rightwards, the distal end member 2 istilted rightwards.

As best shown in FIG. 8, the control box 7 has an outer front surfaceprovided with a display panel 61 of a liquid crystal display type, whichis a rotational condition display section and an attitude displaysection, an initial attitude control indicator lamp 62, an initialattitude operating piece 63 and various operating pieces 64. The initialattitude operating piece 63 and the various operating pieces 64 areemployed in the form of, for example, push button switches. Functions ofthose machine elements will be described in detail later.

Also, as best shown in FIG. 13, a computer 5A used to perform variouscontrols is built in the control box 7. This computer 5A includes a toolrotation control section 71 for controlling the tool rotation drivesource 41 and an attitude control section 53 for controlling theattitude control drive source 42 (42U, 42L and 42R).

The tool rotation control section 71 provides an output signal to amotor driver 73 in dependence on a rotation command signal fed from therotation ON/OFF operating piece 57 to thereby switch the tool rotationdrive source 41 on or off. By so doing, the spindle 13 is driven orhalted. By way of example, if the rotation ON/OFF operating piece 57 ispushed one time, the spindle 13 is rotated, but when the rotation ON/OFFoperating piece 57 is pushed next time, the spindle 13 then rotating ishalted. Conditions required for the rotation of the spindle 13 aredisplayed on the display panel 61 which is the rotational conditiondisplay section. One of those conditions includes, for example, whetheror not the distal end member 2 is properly fixed.

The attitude control section 53 includes an initial attitude holdcontrol unit 53 a and an attitude alteration control unit 53 b.

The attitude alteration control unit 53 b provides an output signal to amotor driver 74 in dependence on an actuation command signal resultingfrom an input manipulation of the attitude altering operation piece 58to thereby drive the attitude control drive source 42 (42U, 42L and42R). By way of example, the amount of drive of the attitude controldrive source 42 is proportional to the operate time of the attitudealtering operation piece 58. When depending on which one of theoperating pieces 58 a, 58 b, 58 c and 58 d is manipulated, the directionof the output and the magnitude of the output for each of the attitudecontrol drive sources 42U, 42L and 42R are changed, the attitude of thedistal end member 2 can be altered.

For example, when the operating piece 58 b is manipulated to provide anoutput signal, such output signal is provided to each of the attitudecontrol drive sources 42U, 42L and 42R. Then, in a manner similar tothat described in connection with the first embodiment of the presentinvention, the upper attitude altering member 31U shown in FIGS. 2A to2D is advanced towards the tip end side and the remaining two attitudealtering members 31L and 31R are retracted. Once this takes place, thehousing 11 for the distal end member 2 is pressed by the upper attitudealtering member 31U with the distal end member 2 consequently altered inattitude along the guide faces f1 and f2 so as to permit the tip endside thereof to be oriented downwards. In the event that the operatingpiece 58 a is manipulated to provide an output signal, each of theattitude altering members 31 is advanced or retracted in a directionreverse to that described above and the housing 11 for the distal endmember 2 is pressed by the left and right attitude altering members 31Land 31R with the distal end member 2 consequently altered in attitudealong the guide faces f1 and f2 so as to permit the tip end side to beoriented upwardly.

Also, in the event that the operating piece 58 c is manipulated toprovide an output signal, such output signal is provided to each of theleft and right attitude control drive sources 42L and 42R to cause theright attitude altering member 31R to advance towards the tip end sideand the left attitude altering member 31L to retract. Then, the housing11 of the distal end member 2 is pressed by the right attitude alteringmember 31R and, consequently, the distal end member 2 is altered inattitude so as to be oriented leftwards, that is, towards the sideforwardly of the plane of the sheet of FIG. 2A, along the guide faces f1and f2. On the other hand, in the event that the operating piece 58 d ismanipulated to provide an output signal, the attitude altering members31L and 31R are advanced or retracted in a manner reverse to those inthe case of manipulating the operating piece 58 c and the housing 11 ofthe distal end member 2 is therefore pressed by the left attitudealtering member 31L, resulting in the attitude of the distal end member2 altered so as to be oriented rightwards along the guide faces f1 andf2.

The attitude of the distal end member 2 is displayed by the displaypanel 61 forming the attitude indicating device. Examples of display soeffected are shown respectively in FIGS. 14A and 14B. Specifically, FIG.14A illustrates angles of tilts of the distal end member 2 in thetwo-axis directions each in terms of a numerical value. By way ofexample, the legend “a” represents the angle of tilt in the up and downdirection (vertical direction) whereas the legend “β” represents theangle of tilt in the leftward and rightward direction (horizontaldirection). FIG. 14B illustrates the direction of tilt of the distal endmember 2 and the angle of tile of the distal end member 2, which areexpressed on the display panel 61 in terms of a point P on the graph. Ifdesired, those two different manners of display appearing on the displaypanel 61 may be selectively displayed one at a time. In such case,arrangement must be made that a display manner changeover command can beapplied to an attitude display control section 75 by means of thevarious operating pieces 64 shown in FIG. 13 to select one of themanners of display discussed above.

In the condition in which the lock operating piece 49 is depressed onetime, the function of the attitude alteration control unit 53 b ishalted. Because of this, even though the attitude altering operationpiece 58 is manipulated, the attitude control drive source 42 will notbe driven and the distal end member 2 is therefore fixed in apredetermined attitude. However, when the lock operating piece 49 isdepressed again, the halt of the function of the attitude alterationcontrol unit 53 b is released and the attitude of the distal end member2 can therefore be altered.

In place of the switching between the function halted condition and thehalted function release condition of the attitude alteration controlunit 53 b, which is accomplished by means of the lock operating piece 49as hereinabove described, arrangement may be made that unless the lockoperating piece 49 is kept depressed, the manipulation of the attitudealtering operation piece 58 is disabled. Conversely, arrangement may bemade that only during the period in which the lock operating piece 49 isdepressed, the manipulation of the attitude alteration piece 58 isdisabled.

The initial attitude hold control unit 53 a is operable to control eachof the attitude control drive sources 42 so that in a manner similar tothat shown and described in connection with the previously describedfirst embodiment of the present invention, the initial attitude holdingforce F0 (FIG. 5) effective to enable the attitude of the distal endmember 2 to be maintained at the arbitrarily preset initial attitude canbe applied to the attitude altering member 31. Also, this initialattitude hold control unit 53 a is operable to perform such a control asto set the distal end member 2 to the initial attitude in response to anactivation command signal generated from the initial attitude operatingpiece 63. Since the initial attitude operating piece 63 is employed and,also, the attitude control section 53 includes the initial attitude holdcontrol unit 53 a, the initial attitude of the distal end member 2 canbe set arbitrarily, the initial attitude can be forcibly resumedmanually, and the initial attitude can be accurately restored. Forexample, immediately after the supply of an electric power to the remotecontrolled actuator is initiated or at the time of initial manipulationsubsequent to replacement of the tool 1, there is the possibility that agap S may be formed between the base end face of the housing 11 of thedistal end member 2 and the pillar shaped pin 31 b of the attitudealtering member 31 as shown in FIG. 15A. For this reason, it isnecessary to remove the gap S by allowing the distal end member 2 toresume the initial attitude. The initial attitude is the attitude, inwhich, for example, the center line CL1 of the distal end member 2 andthe center line CL2 of the spindle guide section 3 are concentricallyaligned with each other as shown in FIG. 15B. The actuation position ofeach of the attitude control drive sources 42 during the initialattitude is stored in a storage section 76. It is to be noted that FIGS.15A and 15B correspond respectively to FIGS. 6 and 5, which pertain tothe previously described first embodiment of the present invention.

The initial attitude control is carried out specifically in the sequenceas shown in the flowchart of FIG. 16. When the initial attitudeoperating piece 63 is manipulated and the actuation command to theinitial attitude position is received (at step S1), each of the attitudecontrol drive sources 42 is retracted (at step S2). The actuationposition of each of the attitude control drive sources 42 is detected bythe attitude detector 48. Once all of the attitude control drive sources42 are retracted to an end of retraction within the range of selectiveadvance and retraction (at step 3), each of the attitude control drivesources 42 is advanced (at step S4). When movement of each of theattitude control drive sources 42 to the arbitrarily preset initialattitude position is completed (at step S5), advance of each of theattitude control drive sources 42 is halted and the movement to theinitial attitude position completes (at step S6). Movement of each ofthe attitude control drive sources 42 to the initial attitude positionconfirms that the actual actuation position of each of the attitudecontrol drive sources 42 indicated by the output from the attitudedetector 48 coincides with the actuation position of each of theattitude control drive sources 42 in the arbitrarily preset initialattitude stored in the storage section 76. The progress of this initialattitude control is step by step displayed by the initial attitudecontrol indicator lamp 62, for example, in such a manner that theindicator lamp 62 is turned off during the uncompleted operation, blinksduring the movement towards the initial attitude position, and is turnedon upon completion of the movement to the initial attitude position. Itis to be noted that the term “uncompleted operation” referred to abovemeans the timing immediately after the remote controlled actuator iselectrically powered on, the timing during which subsequent toreplacement of the tool 1, the movement towards the initial attitudeposition is never effected with the use of the initial attitudeoperating piece 62, and the timing at which during the movement towardsthe initial attitude position, disagreement between the actuationposition of each of the attitude control drive sources 42 detected andthe arbitrarily preset initial attitude stored in the storage section 76occurs.

As hereinbefore described, the remote controlled actuator according tothis embodiment is manipulated with the actuator body 6 held by handsthen gripping the left and right handles 50L and 50R. With the rotationON/OFF operating piece 57 manipulated, the spindle 13 is rotated toallow the tool 1 to undergo cutting of the bone. Since the conditionsrequired for the rotation of the spindle 13 are displayed by the displaypanel 61 serving as the rotational condition display section, thespindle 13 is prevented from being rotated under improper conditions.

During the processing, manipulation of the attitude altering operationpiece 58 according to the shape of a processing site and/or the progressof the processing results in change of the attitude of the distal endmember 2 in the two-axis directions by remote control. When the lockoperating piece 49 is manipulated, the processing can be carried outwhile the distal end member 2 is maintained in the predeterminedattitude. Since the rotation ON/OFF operating piece 57, the attitudealtering operation piece 58 and the lock operating piece 49 can bemanipulated by hand while the left and right handles 50L and 50R aregripped, the operator can use his or her sensory perception to performthe required manipulation and as a result, the intended work can readilybe accomplished. In particular, since the attitude altering operationpiece 58 is in the form of a crisscross switch and the operating pieces58 a, 58 b, 58 c and 58 d are so arranged as to coincide with therespective directions in which the attitude is desired to be altered,the operator can feel the actual alteration of the attitude of thedistal end member 2 through his or her hands touching any one of theoperating pieces 58 a, 58 b, 58 c and 58 d and therefore, alteration ofthe attitude can be accurately and quickly accomplished.

FIGS. 17A to 17C illustrate the distal end member 2 and the spindleguide section 3 both employed in the remote controlled actuator designedaccording to a fourth preferred embodiment of the present invention.This remote controlled actuator includes the guide pipe 30 and theattitude altering member 31 each provided at two locations spaced 90°from each other in the circumferential direction. Those two attitudealtering members 31X and 31Y are independently and selectively advancedor retracted by two attitude control drive sources (not shown),respectively. At a position spaced 180° in phase in the circumferentialdirection relative to the circumferential position at which the attitudealtering member 31 is located, a restoring elastic member 32 in the formof, for example, a compression coil spring is provided between the baseend face of the housing 11 of the distal end member 2 and the distal endface of the outer shell pipe 25 of the spindle guide section 3. Thisrestoring elastic member 32 is operable to bias the distal end member 2towards a predetermined attitude side.

In the construction described above, when the upper attitude alteringmember 31Y shown in FIGS. 17A to 17C is advanced towards the tip endside, the housing 11 of the distal end member 2 is pressed by theattitude altering member 31Y and the distal end member 2 is consequentlyaltered in attitude along the guide faces F1 and F2 with the tip endside oriented downwardly as viewed in FIG. 17A. When the attitudealtering member 31Y is retracted, the housing 11 of the distal endmember 2 is urged to return by the effect of the elastic force ofrepulsion exerted by the corresponding restoring elastic member 32 andthe distal end member 2 is consequently altered in attitude along theguide faces f1 and f2 with its tip end side oriented upwardly as viewedin FIG. 17A. During this attitude altering operation, the pressure ofthe attitude altering member 31, the elastic force of repulsion exertedby the restoring elastic member 32 and the reactive force from theconstraint member 21 act on the distal end member coupling unit 15 and,therefore, the attitude of the distal end member 2 is determined by theeffect of the balance of those forces.

Also, when the right attitude altering member 31X shown in FIGS. 17A to17C is advanced towards the tip end side, the housing 11 of the distalend member 2 is pressed by the attitude altering member 31X and thedistal end member 2 is consequently altered in attitude along the guidefaces f1 and f2 with the tip end side oriented leftwards. When theattitude altering member 31X is retracted, the housing 11 of the distalend member 2 is urged backwards by the effect of the elastic force ofrepulsion exerted by the corresponding restoring elastic member 32 andthe distal end member 2 is consequently altered in attitude along theguide faces f1 and f2 with its tip end side oriented rightwards. Duringthis attitude altering operation, the pressure of the attitude alteringmember 31Y, the elastic force of repulsion exerted by the restoringelastic member 32 and the reactive force from the constraint member 21act on the distal end member coupling unit 15 and, therefore, theattitude of the distal end member 2 is determined by the effect of thebalance of those forces.

As described above, even when the attitude altering members 31X and 31Yand the restoring elastic member 32 are concurrently utilized, theattitude of the distal end member 2 can be altered in the two-axisdirections. Even in such case, the attitude altering drive mechanism(not shown) and the attitude control section (also not shown) are ofrespective structures identical with those described previously.

While in each of the foregoing embodiments of the present invention, thespindle guide section 3 is of a rectilinear shape, the remote controlledactuator of the present invention is such that even when the attitudealtering member 31 has a flexibility and the spindle guide section iscurved, the attitude altering operation of the distal end member 2 canbe performed assuredly. Therefore, the spindle guide section 3 may havea curved shape in its initial state. Alternatively, only a portion ofthe spindle guide section 3 may have a curved shape. If the spindleguide section has a curved shape, it may occur that the distal endmember 2 can be inserted deep into the bone where the spindle guidesection of the rectilinear shape fails to reach and, hence, theprocessing to form the artificial joint insertion hole during theartificial joint replacement surgery can be finished accurately.

While the various preferred embodiments of the present invention havebeen fully described hereinabove, the following mode is available, whichdoes not require the use of the initial attitude hold control unit 53 aof the present invention:

[Mode]

The remote controlled actuator according to this mode includes anelongated spindle guide section, a distal end member fitted to a distalend of the spindle guide section through a distal end member couplingunit for alternation in attitude, and a drive unit housing coupled witha base end of the spindle guide section and capable of being held byhand;

in which the distal end member rotatably supports a spindle for holdinga tool,

in which the spindle guide section includes a rotary shaft fortransmitting rotation of a tool rotation drive source, provided withinthe drive unit housing, to the spindle, and a guide hole defined thereinso as to extend from one end to the opposite end,

in which an attitude altering member for altering the attitude of thedistal end member as a result of advancing or retracting operation withits tip end held in contact with the distal end member is reciprocallymovably inserted within the guide hole,

in which an attitude control drive source for selectively advancing andretracting the attitude altering member is provided within the driveunit housing, and an attitude altering operation piece for changing theattitude of the distal end member by issuing an actuation command signaldirectly or indirectly to the attitude control drive source in responseto an input manipulation is provided outside the drive source housing,and

in which the attitude altering operation piece is capable of beingmanipulated by hands then holding the drive source housing.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings which are used only for the purpose ofillustration, those skilled in the art will readily conceive numerouschanges and modifications within the framework of obviousness upon thereading of the specification herein presented of the present invention.Accordingly, such changes and modifications are, unless they depart fromthe scope of the present invention as delivered from the claims annexedhereto, to be construed as included therein.

REFERENCE NUMERALS

-   -   1: Tool    -   2: Distal end member    -   3: Spindle guide section    -   4 a: Drive unit housing    -   5: Controller    -   5A: Computer    -   6: Actuator body    -   7: Control box    -   13: Spindle    -   15: Distal end member coupling unit    -   22: Rotary shaft    -   25: Outer shell pipe    -   30: Guide pipe    -   30 a: Guide hole    -   31: Attitude altering member    -   34: Reinforcement shaft    -   41: Tool rotation drive source    -   42: Attitude control drive source    -   43: Force increasing and transmitting mechanism    -   45: Reverse input preventing mechanism    -   46: Actuation amount detector    -   47: Strain sensor    -   48: Attitude detector    -   49: Lock operating piece    -   50L, 50R: Handle    -   51: Attitude setting device    -   53: Attitude control section    -   53 a: Initial attitude hold control unit    -   53 b: Attitude alteration control unit    -   54: External force estimating section    -   57: Rotation ON/OFF operating piece    -   58: Attitude altering operation piece    -   61: Display panel (Rotational condition display section,        Attitude display section)    -   63: Initial attitude operating piece    -   71: Tool rotation control section    -   76: Storage section

1. A remote controlled actuator, which comprises: a spindle guidesection of an elongated shape, a distal end member fitted to a distalend of the spindle guide section through a distal end member couplingunit for alteration in attitude, and a drive unit housing coupled with abase end of the spindle guide section; wherein the distal end memberrotatably supports a spindle for holding a tool, wherein the spindleguide section includes a rotary shaft for transmitting rotation of atool rotation drive source, provided within the drive unit housing, tothe spindle and a guide hole defined therein so as to extend from oneend to the opposite end, wherein an attitude altering member having atip end held in contact with the distal end member is reciprocallymovably inserted within the guide hole, wherein an attitude controldrive source for applying to the attitude altering member a force actingin a direction of advance and retraction is provided within the drivesource housing and, also, an attitude control section for controllingthe attitude control drive source is provided, and wherein the attitudecontrol section includes an initial attitude hold control unit forcontrolling the attitude control drive source to apply to the attitudealtering member an initial attitude holding force necessary to enablethe attitude of the distal end member to hold in an arbitrarily presetinitial attitude, and an attitude alteration control unit forcontrolling the attitude control drive source to apply to the attitudealtering member a force greater than the initial attitude holding forcebeing applied to the attitude altering member so that the attitude ofthe distal end member is altered by selectively advancing or retractingthe attitude altering member.
 2. The remote controlled actuator asclaimed in claim 1, in which the attitude of the distal end member isdetermined in dependence on an amount of reciprocal movement of theattitude altering member relative to a reference position, which isdefined as a position of the attitude altering member assumed when thedistal end member is in the initial attitude.
 3. The remote controlledactuator as claimed in claim 2, further comprising an attitude settingdevice for setting a target attitude of the distal end member, whereinthe attitude alteration control unit is operable to convert the targetattitude of the distal end member, preset by the attitude settingdevice, into an amount of advance or retraction of the attitude alteringmember, which corresponds thereto, and to change an amount of actuationof the attitude control drive source in dependence on the amount ofadvance or retraction so converted.
 4. The remote controlled actuator asclaimed in claim 3, further comprising an actuation amount detector fordetecting the amount of actuation of the attitude control drive sourceand feeding an output thereof back to the attitude alteration controlunit.
 5. The remote controlled actuator as claimed in claim 1, furthercomprising a reverse input preventing mechanism for preventing theattitude control drive source from actuating by the effect of a forcefrom the distal end member, which mechanism is provided in the attitudecontrol drive source or between the attitude control drive source andthe distal end member.
 6. The remote controlled actuator as claimed inclaim 1, in which the attitude control drive source is an electricallydriven actuator, the electrically driven actuator being driven by anelectric power of PWM wave.
 7. The remote controlled actuator as claimedin claim 1, in which the attitude control drive source is a linearactuator and further comprising a force increasing and transmittingmechanism for increasing a thrust force of the linear actuator and thentransmitting it to the attitude altering member, the force increasingand transmitting mechanism being comprised of a lever mechanism.
 8. Theremote controlled actuator as claimed in claim 7, further comprising astrain sensor for detecting a strain occurring in the lever of the forceincreasing and transmitting mechanism, and an external force estimatingsection for estimating an external force, acting on the distal endmember, in reference to an output of the strain sensor.
 9. The remotecontrolled actuator as claimed in claim 1, further comprising anattitude altering operation piece provided outside the drive sourcehousing for altering the attitude of the distal end member by causing anactuation command signal to be generated to the attitude control drivesource through the attitude alteration control unit by means of an inputmanipulation, and in which the attitude altering operation piece iscapable of accomplishing the input manipulation by hands then holdingthe drive unit housing.
 10. The remote controlled actuator as claimed inclaim 9, in which the distal end member coupling unit supports thedistal end member for tilting motion in arbitrary direction, in whichthe guide hole and the attitude altering member inserted within theguide hole are provided at three or more locations about a center oftilt of the distal end member, in which the attitude control drivesource is provided for each of the attitude altering members, and inwhich the attitude of the distal end member is altered or maintained byan effect of balance of working forces applied from the attitudealtering members at those three or more locations to the distal endmember.
 11. The remote controlled actuator as claimed in claim 9, inwhich the distal end member coupling unit supports the distal end memberfor tilting motion in arbitrary directions, in which the guide hole andthe attitude altering member inserted within the guide hole are providedat a plurality of locations about a center of tilt of the distal endmember, in which the attitude control drive source is provided for eachof the attitude altering members, in which a restoring elastic memberfor biasing the distal end member to hold a predetermined attitude isprovided, and in which the plural attitude altering members cooperatewith each other to alter the attitude of the distal end member against abiasing force exerted by the restoring elastic member.
 12. The remotecontrolled actuator as claimed in claim 9, in which the attitudealtering operation piece is operable to alter the attitude of the distalend member in two directions when an actuation command signal is issuedto each of the attitude control drive sources and is manipulatable intwo directions corresponding to directions in which the attitude of thedistal end member is altered.
 13. The remote controlled actuator asclaimed in claim 9, further comprising a lock operating piece providedfor disabling an input manipulation of the attitude altering operationpiece.
 14. The remote controlled actuator as claimed in claim 9, furthercomprising: an attitude detector for detecting the attitude of thedistal end member; and an attitude display section for displaying theattitude of the distal end member detected by the attitude detector. 15.The remote controlled actuator as claimed in claim 14, in which theattitude detector is an encoder for detecting an actuation position ofthe attitude control drive source.
 16. The remote controlled actuator asclaimed in claim 9, further comprising an attitude control section forcontrolling the attitude control drive source in dependence on anactuation command signal generated from the attitude altering operationpiece.
 17. The remote controlled actuator as claimed in claim 9, furthercomprising an initial attitude operating piece for issuing an actuationcommand signal, necessary to cause the distal end member to assume theinitial attitude, through the initial attitude hold control unit. 18.The remote controlled actuator as claimed in claim 17, furthercomprising a storage section for storing an actuation position of theattitude control drive source when the distal end member is in theinitial attitude, and in which the initial attitude hold control unit ofthe attitude control section is operable to control the attitude controldrive source so as to assume the actuation position, stored in thestorage section, that when the initial attitude operating piece isoperated.
 19. The remote controlled actuator as claimed in claim 9,further comprising a rotation operating section for operating therotation of the spindle, the rotation operating section being capable ofbeing operated by hands then holding the drive unit housing.